In the textile industry, there are a whole variety of production machines on which operation is performed simultaneously at a plurality of work stations or production points. Examples which may be given are spinning frames, winding frames or twisting frames.
There is a need to monitor automatically each one of these production points with regard to production sequence and quality produced. From the point of view of the production sequence, thread breakage monitoring is desired in particular and, from the point of view of quality monitoring, determination of the thread cross-section and/or thread irregularity is desired. In the case of twisting frames, the twist cross-section is of interest in particular, as a check on whether all threads have been taken up in the twist.
The following text and claims always refer to "thread". This term is not to be understood as restrictive, but as representative for all spinning products, such as yarns, rovings, slubbings, twisted yarns, strands, filaments and the like.
The monitoring of all individual production points could in itself be accomplished by known means, but such has not yet been put into practice for reasons of cost. This is so since the plurality of production points only allows a minimum expenditure per production point in order that the outlay per frame remains within reasonable limits.
For thread breakage detection on ring spinning frames, recently systems have appeared on the market which have so-called traveler sensors. See for example U.S. Pat. No. 4,122,657. In this case, movement of the ring travelling on the entire side of a ring spinning frame can be detected with a single sensor. In terms of cost, this solution is reasonable for thread breakage detection. However, a measurement of further thread parameters is not possible, because the signal is generated by the rotating ring traveler and not by the thread itself. In addition, the time between the occurrence of a thread breakage and its detection is often much too long in the case of traveling sensors.
So far, no cost-effective solutions have been put into practice on ring spinning, twisting and such like frames for determination of the thread cross-section and/or the irregularity of the same directly at the production point.